ABCB4 and hepatocellular carcinoma: Diubiquitin is involved in the maintenance of spindle integrity during mitosis and is highly upregulated in human HCC [27]; it was detected mostly in the cytoplasm of hepatocytes in the tumors of Mdr2-KO/HCV-Tg mice, and, to a lesser degree, in non-tumorous liver tissues of Mdr2-KO mice with or without the HCV transgene (Fig. 6).